The invention pertains to a bearing or roller bearing with an information sensor, of the type comprising a stationary element carrying at least one magnetic field sensor device and one rotating element carrying a multipole magnetized ring coaxial to said rotating element, which moves in front of the sensor device, and in which the ring is mounted in a nonmagnetic support carried by said rotating element and is separated from the sensor device by an air gap. One such bearing has been described in U.S. Pat. No. 4,732,494.
More specifically, the invention pertains to a process for producing the magnetized ring with good magnetization precision. Another object of the invention is a sealed roller bearing with information sensor which makes use of the magnetized ring.